<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <link rel="stylesheet" href="../css/reset.css">
    <style>
        .a {
            /* width: 100%; */
            height: 100px;
            background-color: #ddd;
        }

        .a1 {
            width: 1205px;
            height: 100px;
            margin: auto;
            background-color: #ff0;
        }
    </style>
</head>

<body>

    <div class="a">
        <div class="a1"></div>
    </div>


    <div class="b">
        <div class="b1"></div>
    </div>


    <div class="c">
        <div class="c1"></div>
    </div>

</body>

</html>